The field-effect modified transistor: a high-responsivity photosensor

A new photosensing device that can be described as a field-effect modified bipolar transistor, has been developed. A novel technique of reducing the effective collector capacitance without reducing the total primary photocurrent provides for a decade improvement in responsivity for the FEM phototransistor operating in the charge-storage mode. Other applications of this device include a high noise-immunity inverter, a light intensity-to-frequency converter, and a simple semiconductor memory element. FEM transistors can be fabricated using the same processing schedule used for conventional bipolar transistors; no additional steps are required.